Abstract

Pollenanalytic investigations indicate that the uppermost Pliocene deposits in the Ville area (clay-horizon A) belongs to the Reuverium B to C. These sediments still contain a typical Pliocene molluscan fauna. At their base (boundary clay-horizon A1 to A2) the heavy mineral assemblage changes from a tourmaline-zircon-staurolite assemblage to a spectrum containing garnet-epidote-alterite-green hornblende. Within this clay-horizon A the paleomagnetic polarisation changes from normal direction in the lower part to reverse direction in the upper part. This change of polarity is believed to be the boundary between the GAUSS- and MATUYAMA-magnetic epoche. The uppermost part of clay-horizon A again shows normal magnetisation. The overlying sediments are still of Pliocene type (gravel b1) but the following clay-horizon is marked by a Quarternary flora of a temperate climate (clay-horizon B1). This clay-bed is overlain by a typical Quarternary gravel which, in turn, is followed by a clay-bed (B2) containing a typical interglacial molluscan fauna and characterised by reverse magnetic polarisation. The Pliocene/Pleistocene boundary is thought to be between clay-horizon A and gravel b1. Within the paleomagnetic time scale, the section should be placed between the Oulduvai-event, about 1,8-2,0 millions years, and the GAUSS-MATUYAMA-boundary, about 2,45 millions years.